The European landmass lies to the south and east of Britain, the Asian landmass to the north and west of Japan. A newspaper headline in Britain once famously declared: "Fog over the channel, continent isolated." Japan may lack such endearing chauvinism, but is far more homogeneous and closed as a society than Britain, especially modern Britain. Japan is geographically more distant from the Asian mainland, yet metaphorically closer to Asia than is Britain is to Europe.
After World War II, Britain lost an empire but gained a role. Before that war, Japan gained an empire but lost its international role in the aftermath of a bitter and complete defeat. The British empire, on which the sun never set, was in other parts of the world, never in Europe. The Japanese empire, on which the sun set very quickly indeed, was only in Asia. The British attitude of superiority toward all things continental is therefore based on factors other than having been the colonial master. Japan's relations with much of Asia is still heavily colored on both sides by the history of colonial enterprise and the brutal policies that often accompanied it.
The politics of identity is complex and volatile, as we discovered in the Balkans and East Timor during the last decade. So much of modern Japan has its origins in things borrowed from Asia over many centuries, not just China as is most obvious, but also India (for example, the influence of Buddhism). Yet Japan's drive to modernization and industrialization was so successful that Japanese could be forgiven for thinking that they had left their continental identity far behind and were really part of the industrial West rather than pre-industrial Asia.